Method and device for stopping an internal combustion engine with fuel injection in case of overspeed

ABSTRACT

Method and device for stopping in case of overspeed an internal combustion engine having fuel injection pumps of the constant stroke, reciprocating piston type, in which a pad defines in the pump body two separate closed chambers, wherein a compressed inert gas is fed in the second chamber for separating the pump piston from its tappet and thereby stopping the injection pump.

United States Patent [1 1 Bastenhof 1 Dec. 16, 1975 METHOD AND DEVICEFOR STOPPING AN INTERNAL COMBUSTION ENGINE WITH FUEL INJECTION IN CASEOF OVERSPEED [75] Inventor: Dirk Bastenhof, Eaubonne, France [73]Assignee: Societe dEtudes de Machines Thermiques, Saint Denis, France[22] Filed: May 28, 1974 [21] Appl. No.: 473,940

[30] Foreign Application Priority Data June 26, 1973 France 73.23380[52] US. CL. 123/139 AZ; 123/198 D; 123/198 DB [51] Int. Cl. F02B 77/00[58] Field of Search... 123/139 AZ, 198 D, 198 DB;

[56] References Cited UNITED STATES PATENTS 2,638,053 5/1953 Nicollsl23/l39.13

Alfieri 92/129 Stolworthy 123/198 DB Primary E.raminer-Wendell E. BurnsAssistant E.\'aminerPaul Devinsky Attorney, Agent, or Firm-Kenyon &Kenyon Reilly Carr & Chapin 5 7 ABSTRACT Method and device for stoppingin case of overspeed an internal combustion engine having fuel injectionpumps of the constant stroke, reciprocating piston type, in which a paddefines in the pump body two separate closed chambers, wherein acompressed inert gasis fed in the second chamber for separating the pumppiston from its tappet and thereby stopping the injection pump.

11 Claims, 1 Drawing Figure US. Patent Dec. 16, 1975 METHOD AND DEVICEFOR STOPPING AN INTERNAL COMBUSTION ENGINE WITH FUEL INJECTION IN CASEOF OVERSPEED The present invention relates essentially to a method ofstopping an internal combustion engine with fuel injection, includingfuel-injection pumps of the constant stroke, reciprocating piston type,in case of overspeed and attendant danger of racing.

The invention relates also to an emergency stop de vice for carrying outthis method as well as to the various applications and uses thereof andto the systems, assemblies, apparatus, vehicles, engines, plants,equipments and installations fitted with such a device (see, e.g. FrenchPat. No. 2,120,400, corresponding to US. Pat. No. 3,750,640).

There are already known devices in which, in case of overspeed ofaninternal combustion engine with fuel injection, an overspeed-sensitiveor overspeed-responsive triggering or tripping member or like releasedevice opens a pressure-fluid supply valve for feeding one or severalpower cylinder actuators or like servomotors the pistons of which willact upon the control racks operating the injection pumps so as to stopor discontinue the fuel injection provided by all pumps. A significantdisadvantage of these devices is that they cannot work upon anaccidental blockin'g or jamming of the rack or of the mechanicaltransmission, drive or gear connected between the power cylinders andthe rack.

There are also known devices for stopping the injection pumps by meansof hydraulic ram actuators which are fitted each one on an injectionpump and which are supplied in case of overspeed of the engine with afluid under pressure enabling to displace the piston of each ramactuator and to convey the motion of the piston of the ram actuator tothe piston of the injection pump by means of a lever for separating saidpiston from its tappet, push-rod or like lifter and from its operatingcam. The disadvantage of such a device is its relative complexity andits high cost price.

The invention therefore provides a process and a particularly simpledevice for stopping the fuel injection pumps in case of overspeed of theinternal combustion engine, which are quite reliable and the cost priceof which is relatively low.

According to the invention, the method of stopping in case of overspeedan internal combustion engine including fuel injection pumps of theconstant strokereciprocating piston type and in which a bolster or padLe, a hollow cylinder closed at one end sliding within the pump body andinterposed between the piston and its operating tappet, push-rod orlifter defines within the pump body two separated closed chambers thefirst one of which contains the piston and the second or other onecontains the tappet, is characterized in that it consists, in case ofoverspeed of the engine, in feeding a compressed gaseous fluid into saidsecond chamber with a pressure high enough for disengaging andseparating as known per se said bolster or pad hence said piston fromsaid tappet and thereby stopping the corresponding injection pump.

Thus according to the invention a compressed fluid such as air orpreferably an inert gas such as nitrogen or carbon dioxide is directlyadmitted inside of the pump body so as to cause the pressure of this gasto act upon the pad or bolster interposed between the pump piston andits operating tappet for separating the piston from the tappet andthereby cutting off or discontinuing the fuel injection by the pumpinvolved.

The device for stopping, in case of overspeed, an in ternal combustionengine with fuel injection including injection pumps of the constantstroke-reciprocating piston type, in which the piston is separated fromits operating tappet by a sliding pad or member defining within the pumpbody or casing a pair of separated closed chambers the first one ofwhich houses the piston and the second one of which contains the tappetand is provided with a fuel drain or leakage recovering or collectingduct, is characterized according to the invention in that it comprisesmeans enabling feeding into said second chamber a compressed fluid incase of overspeed of the engine with a pressure high enough fordisengaging and separating in a manner known per se said pad hence saidpiston from said actuating tappet and thereby stopping each fuelinjection pump.

The device according to the invention is therefore considerablysimplified with respect to the known prior state of the art as it doesno longer comprise power cylinders or ram actuators adapted to act uponthe racks or upon a lever for separating the pump piston from itsactuating tappet.

According to another characterizing feature of the invention thecompressed gaseous fluid feed means comprise a compressed gaseous fluidsource or supply connected by an overspeed-sensitive triggering deviceor like overspeed-responsive release contrivance to said fuel leakagerecovering duct within said second chamber.

Thus according to the invention the fuel leakage recovering duct is usedto feed the compressed fluid into the inside of the pump body or casing.

The invention will be better understood and further objects,characterizing features, details and advantages thereof will appear moreclearly as the following explanatory description proceeds with referenceto the accompanying diagrammatic drawing given by way of non-limitingexample only illustrating a presently preferred form of embodiment ofthe invention and wherein the single FIGURE shows a partial longitudinalsectional view of an injection pump used in the emergency stop deviceaccording to the invention.

The method and the device for stoppage according to the invention aretherefore intended for use on internal combustion engines with fuelinjection including fuel injection pumps 1 having a constant-strokereciprocating piston 12. This piston 12 is driven according to atranslatory motion by means of a tappet or like lifter or pusher member3 resting through a follower or like roller 4 on an operating cam 5. Apad or member 6 which is a hollow cylinder closed at one end is slidablymounted within the body or casing 7 of the pump 1 and is interposedbetween the piston 12 and its operating tappet 3. This pad or memberthereby defines within the body or casing of the pump 1 a pair ofseparated closed chambers 8 and 9 the first one of which contains thepiston 12 and the second one of which contains the tappet 3. This secondchamber is provided at its bottom portion with a fuel leakage recoveringduct 10.

The piston 12 is also operatively or drivingly rotated by means of agear or pinion 2 through a toothed rack 11 which is diagrammaticallyshown in cross-section and which enables adjustment of flow rate of theinjected fuel through rotation of the piston 12 in a manner known perse.

It may happenthat the toothed rack. 11 is blocked or jammed in aposition corresponding to the maximum flow rate of injected fuel, forvarious grounds, for instance in view of scoring or seizing or in thepresence of dirt. In such a case the engine exhibits a tendency to raceand it becomes necessary to stop it forthwith by discontinuing the fuelinjection. For this purpose the invention contemplated to feed acompressed gaseous, preferably inert fluid such as nitrogen or carbondioxide, into the second chamber 9 containing the tappet, thiscompressed gas having a pressure high enough to overcome the opposingbiasing force of the piston drawback or return spring 13 and thereby tofully disengage and separate the pad or member 6 of the piston.

12 from the drive tappet 3. There is no longer any fuel injection andthe engine stops.

The admission of compressed gaseous fluid into the chamber 9 is carriedout very easily by means of the fuel leakage recovering duct or pipe 10which is then connected to a source or supply of compressed air operatedby an engine overspeed-sensitive triggering device 16.

The upper or top chamber 8 containing the piston 12 is advantageouslyprovided with a means 17 for venting same to the outer atmosphere, suchfor instance as a calibrated safety valve, a check valve or a simplebreather or snifting-valve so as to avoid the building up within thischamber 8 of too high a pressure caused by the compressed gaseous fluidleakages from the chamber 9 to this chamber 8. Thereby is also avoidedthe clogging or fouling of the toothed rack 11 by dirt'or fuel leakswhich would climb up towards the toothed rack under the action of thispressure within the chamber 8.

The device provided by the invention is therefore considerablysimplified with respect to the known prior art and its operation is muchmore reliable.

The pad or member 6 used may thus be provided without communicationholes or passageways between the chambers 8 and 9 as depicted in thedrawings or it may be formed with thoroughfare holes extendingtherethrough and providing a communication between the chambers 8 and 9,these holes being provided with valves allowing passage of a compressedgaseous fluid from chamber 8 to chamber 9 only. Thus the invention isvery easily applicable to previously known injection pumps.

It should be understood that the invention is not at all limited to theform of embodiment described and shown which has been given by way ofexample only. In particular it comprises all the means constitutingtechnical equivalents of the means described as well as theircombinations if same are carried out according to the gist and usedwithin the scope of the appended claims.

What is claimed is:

1. A method of stoppingan internal combustion engine, in case ofoverspeed, including fuel injection pumps of the constant-stroke,reciprocating piston type, each of said pumps comprising a pump body,having a pump cylinder and an intermediate cylinder adjacent to and inalignment with the pump cylinder, a pump piston in the pump cylinder, adrive tappet for driving said piston, an intermediate drive pistondisposed in the intermediate cylinder between said pump piston and saiddrive tappet and being combined there with, said intermediate drivepiston defining within said body a pair of separated closed chambers, afirst one of which contains said pump piston and a second one of whichcontains said tappet, said method comprising a source of pressurizedgaseous fluid sensing an engine overspeed condition, and feeding inresponse to the sensing of overspeed of the engine pressurized gaseousfluid from the source into the second chamber, the pressurized gaseousfluid having a pressure high enough when fed into the second chamber tourge the intermediate drive piston toward the first chamber and todisengage and separate the intermediate drive piston and thereby thepump piston from being driven by the drive tappet and to thereby stopthe corresponding injection pump.

2. A method according to claim 1, wherein said gaseous fluid is an inertgas.

3. A method according to claim 1, wherein said gaseous fluid is air.

4. A device for stopping an internal combustion engine in case ofoverspeed including fuel injection pumps of the constant-stroke,reciprocating piston type, each of said pumps comprising a pump body, apiston, a drive tappet for driving the piston, a hollow cylinder closedat one end and slidably mounted within said pump body between saidpiston and said tappet and defining within said pump body a pair ofseparated closed chambers, a first one of which contains said piston andthe second one of which contains said tappet, said device comprising asource of pressurized gaseous fluid, and means for providing acommunication between said source and said second chamber for feedingsaid pressurized gaseous fluid into said second chamber, said gaseousfluid having a pressure high enough for disengaging and separating saidhollow cylinder and thereby said piston from said drive tappet tothereby stop said injection pump.

5. A device according to claim 4, wherein said second chamber has a fuellead recovering duct extending from the interior to the exterior of thesecond chamber, valve means for connecting the duct to the source ofpressurized gaseous fluid and an overspeed-sensitive triggering deviceconnected to the valve means for releasing pressurized gaseous fluidinto the duct in response to an overspeed condition.

6. A device according to claim 4, wherein said gaseous fluid is an inertgas.

7. A device according to claim 4, wherein said gaseous fluid is air.

8. A device according to claim 4, wherein said first chamber includesventing means for allowing the exhaust of pressurized gaseous fluidleaks flowing from said second chamber into said first chamber.

9. A device according to claim 8, wherein said venting means is a checkvalve.

10. A device according to claim 8, wherein the venting means is asnifting-valve.

1 l. A device according to claim 8, wherein said injection pumpcomprises a control toothed rack, and said venting means comprisesgrooves formed in said

1. A method of stopping an internal combustion engine, in case ofoverspeed, including fuel injection pumps of the constant-stroke,reciprocating piston type, each of said pumps comprising a pump body,having a pump cylinder and an intermediate cylinder adjacent to and inalignment with the pump cylinder, a pump piston in the pump cylinder, adrive tappet for driving said piston, an intermediate drive pistondisposed in the intermediate cylinder between said pump piston and saiddrive tappet and being combined therewith, said intermediate drivepiston defining within said body a pair of separated closed chambers, afirst one of which contains said pump piston and a second one of whichcontains said tappet, said method comprising a source of pressurizedgaseous fluid sensing an engine overspeed condition, and feeding inresponse to the sensing of overspeed of the engine pressurized gaseousfluid from the source into the second chamber, the pressurized gaseousfluid having a pressure high enough when fed into the second chamber tourge the intermediate drive piston toward the first chamber and todisengage and separate the intermediate drive piston and thereby thepump piston from being driven by the drive tappet and to thereby stopthe corresponding injection pump.
 2. A method according to claim 1,wherein said gaseous fluid is an inert gas.
 3. A method according toclaim 1, wherein said gaseous fluid is air.
 4. A device for stopping aninternal combustion enGine in case of overspeed including fuel injectionpumps of the constantstroke, reciprocating piston type, each of saidpumps comprising a pump body, a piston, a drive tappet for driving thepiston, a hollow cylinder closed at one end and slidably mounted withinsaid pump body between said piston and said tappet and defining withinsaid pump body a pair of separated closed chambers, a first one of whichcontains said piston and the second one of which contains said tappet,said device comprising a source of pressurized gaseous fluid, and meansfor providing a communication between said source and said secondchamber for feeding said pressurized gaseous fluid into said secondchamber, said gaseous fluid having a pressure high enough fordisengaging and separating said hollow cylinder and thereby said pistonfrom said drive tappet to thereby stop said injection pump.
 5. A deviceaccording to claim 4, wherein said second chamber has a fuel leadrecovering duct extending from the interior to the exterior of thesecond chamber, valve means for connecting the duct to the source ofpressurized gaseous fluid and an overspeed-sensitive triggering deviceconnected to the valve means for releasing pressurized gaseous fluidinto the duct in response to an overspeed condition.
 6. A deviceaccording to claim 4, wherein said gaseous fluid is an inert gas.
 7. Adevice according to claim 4, wherein said gaseous fluid is air.
 8. Adevice according to claim 4, wherein said first chamber includes ventingmeans for allowing the exhaust of pressurized gaseous fluid leaksflowing from said second chamber into said first chamber.
 9. A deviceaccording to claim 8, wherein said venting means is a check valve.
 10. Adevice according to claim 8, wherein the venting means is asnifting-valve.
 11. A device according to claim 8, wherein saidinjection pump comprises a control toothed rack, and said venting meanscomprises grooves formed in said toothed rack.